Electronic ignition system for firearms

ABSTRACT

An electronic ignition system for firing electrically primed ammunition in a firearm. The system includes a trigger for converting mechanical movement to electrical signals without the need of electrical contacts, and logic circuitry which permits selective firing of multiple barrels with a single trigger. Various electrical and mechanical safety features, including retractable firing pins, are provided to prevent accidental discharge of the weapon.

United States Patent 7 [1 1 3,650,174 Nelsen 51 Mar. 21, 1972 [54]ELECTRONIC IGNITION SYSTEM FOR 3,505,927 4/ l 970 Driscoll ..89/ l 35FIREARMS 2,780,882 2/l957 Temple ..42/84 3,208,181 9/1965 Calhoun et al..42/84 [72] Inventor: Thomas Sloan Nelsen, 616 Foothill Road,

Sanford, Calif. 90005 FOREIGN PATENTS 0R APPLICATIONS [22] Filed: Jan.12, 1970 2,629 1908 Great Britain ..42/84 [21] Appl.No.: 2,274

Related U.S. Application Data [63] Continuation-impart of Ser. No.820,932, May 1,

I969, abandoned. [57] Primary Examiner-Benjamin A. Borchelt AssistantExaminer-Stephen C. Bentley AttorneyFlehr, l-lohbach, Test, Albritton &Herbert ABSTRACT An electronic ignition system for firing electricallyprimed am- 2 l ..89 28 42 42,8 127, [5 l U s C l 9/ munition 1n afirearm. The system includes a trigger for con- 42/84 51 1 Int. Cl...F4lc 19/12 F41f 13/08 vemng mechafllcal "memem to elecmcal lgnalswithout the 58] Fie|d f Search 42/42 89/58 127 135 need of electricalcontacts, and logic circuitry which permits IIIIIIIIIIIIIIIIII uselective firing of multiple barrels with a single trigger. Van'- [56References Cited ous electrical and mechanical safety features,including 7 retractable firing pins, are provided to prevent accidentalUNITED STATES PATENTS discharge of the weapon.

937,396 10/1909 Venier ..42/42 11 Claims, 11 Drawing Figures Fl RI NG PIN TRIGGER CONTROL FIRING AND MEANS CIRCUIT CIRCUIT CARTRIDGE I l3 /6 l?PIN FIRING FIRING FIRLNNGD SEQUENCE CIRCUIT SELECTOR CARTRIDGE 23 ,22POWE R I POW ER S U P PLY S U P P LY PAIENIEDMIIRZI I972 3,650,174

SHEET 1 OF 4 E r /5 TRIGGER CONTROL FIRING 'gz PIN N MEA s CIRCUITCIRCUIT CARTRIDGE I H I I6 /7 FIRING FIRING FIRING PIN SEQUENCE CIRCUITAND SELECTOR CARTRIDGE POWER POWER SUPPLY SUPPLY TO CONTROL CIRCUIT l2TO CONTROL CIRCUIT I2 INPUT FROM CONTROL CIRCUIT INVENTOR.

THOMAS S. NELSEN ATTORNEYS T0 FIRING PIN 26 PAIENIEBMARZI I972 3.650.174

SHEET 2 OF 4 INVENTOR. THOMAS 5. NELSEN ATTORN E Y5 PATENIEBMIIRZI I9723.650.174

SHEET 3 [IF 4 4 INPUT FROM 8! 82 83 TRIGGER CIRCUIT 87 88 TO uPPERBARREL FIRING CIRCUIT 93 92 TO LowER BARREL FIRING CIRCUIT INPUT FROMI82 TRIGGER CIRCUIT I8! 'I I88 TO uPPER BARREL FIRING cIRcuIT 1 I92 I93Rs I94 C s 0 TO LowER BARREL 'FIRING CIRCUIT INVENTOR. THOMAS S NELSENWJM ATTORNEYS PAIENTEUMARZI m2 3 650,174

' SHEET u BF 4 77 2670 I9 4% 51% & SCR- I21 l' C- I27 A 0 TO FIRING PIN26 INVENTOR. THOMAS S. NELSEN BY ZA//MZ M ATTORNEYS ELECTRONIC IGNITIONSYSTEM FOR FIREARMS BACKGROUND OF THE INVENTION This invention pertainsgenerally to firearms and more particularly to an electronic system forfiring electrically primed ammunition.

In conventional firearms, a mechanical striker including a hammer andfiring pin is provided for detonating percussion primers. A time lag,known as lock time, between trigger pull and ignition of the ammunitionis inherent in this type of firing mechanism. The delay is caused by themechanical inertia of the hammer and firing pin and typically variesfrom several milliseconds to tens of milliseconds. Mechanical systemsare also subject to wear, with consequent deterioration of performance.

Weapons heretofore provided for firing ammunition by electrical meanshave included electrical contacts, piezo-electric crystals, and/or meansfor electrically releasing a mechanical striker. These systems all havedrawbacks, such as the unreliability of electrical switches and a timedelay in the firing mechanism. Furthermore, such systems generallyrequire a separate trigger for each barrel of the weapon.

There is, therefore, a need for a new and improved ignition system forfirearms which overcomes the foregoing and other problems encounteredwith firing systems. heretofore provided.

SUMMARY AND OBJECTS OF THE INVENTION The present invention provides anelectronic ignition system for firearms which has no mechanical contactsin its firing circuit. The system substantially eliminates the timedelay of the firing mechanism, or lock time, and permits multibarreloperation from a single trigger without double ignition and withoutdeterioration of performance with use. This system utilizessemiconductor devices and can be powered by small batteries which areeasily carried by the firearm.

It is in general an object of the present invention to provide a new andimproved electronic ignition system for firing electrically primedammunition in a firearm.

Another object of the invention is to provide an ignition system of theabove character having no mechanical electrical contacts in its firingcontrol circuit.

Another object of the invention is to provide an ignition system of theabove character which includes means for preventing accidental dischargeof the firearm.

Another object of the invention is to provide an ignition system of theabove character wherein a single trigger selectively controls the firingmultiple barrels.

Another object of the invention is to provide an ignition system of theabove character which includes electronic means for controlling thefiring order of multi-barrel weapons.

Another object of the invention is to provide an ignition system of theabove character which includes means for preventing multiplesimultaneous ignition of the ammunition in different barrels of theweapon.

Another object of the invention is to provide an ignition system of theabove character wherein the pull and travel of the trigger can beadjusted over wide ranges without danger of accidental discharge of theweapon when they are adjusted to low values.

Another object of the invention is to provide an ignition system of theabove character wherein the firing pins are retracted at all timesexcept when the breech is closed and locked to prevent accidentaldischarge of the ammunition in a partially open weapon.

Additional objects and features of the invention will be apparent fromthe following description in which the preferred embodiments are setforth in detail in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWing FIG. 1 is a block diagram of oneembodiment of an electronic ignition system incorporating the presentinvention.

FIG. 2 is a cross-sectional view of the firing chamber of a two-barrelover-under type firing arm having retractable firing pins incorporatingthe present invention.

FIG. 3 is a elevational view of one embodiment of a triggerincorporating the present invention.

FIG. 4 is a circuit diagram of the trigger circuit which is particularlysuitable for use with the trigger embodiment shown in FIG. 3.

FIG. 5 is an elevational view of a second embodiment of a triggerincorporating the present invention.

FIG. 6 is a circuit diagram of a trigger circuit which is particularlysuitable for use with the trigger embodiment shown in FIG. 5.

FIG. 7 is a circuit diagram of one embodiment of a control circuitincorporating the present invention.

FIG. 8 is a circuit diagram of another embodiment of a control circuitincorporating the present invention.

FIG. 9 is a circuit diagram of one embodiment of a firing circuitincorporating the present invention.

FIG. 10 is an elevational view of one embodiment of the triggerutilizing a pressure-sensitive silicon controlled rectifier andincorporating the present invention.

FIG. 11 is a schematic diagram of a combined trigger circuit and firingcircuit which is particularly suitable for use with the triggerembodiment shown in FIG. 10.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the preferred embodiment ofthe electronic ignition system illustrated in FIG. 1, a single triggercontrols the firing of two separate barrels. This system includesgenerally trigger means 11, a control circuit 12, a firing sequenceselector 13, a first firing circuit 14 and firing pin and cartridge 15associated with one barrel of the gun, and a second firing circuit 16and a firing pin and cartridge 17 associated with the second barrel.Power is supplied to the trigger means 11, control circuit 12, andfiring sequence selector 13 by means of a first power supply 21, and tothe firing circuits l4 and 16 by a second power supply 22. A safetyswitch 23 is connected between the power supply 22 and the firingcircuits to provide means for removing the power from the firingcircuits to prevent accidental discharge of the gun. This switch canalso be used to conserve power when the gun is not in use. Similarly, anon-off switch 24 is provided between the power supply 21 and thecircuits which it supplies.

FIG. 2 illustrates firing pins embodying the present invention in anover-under type of double-barrel weapon. One firing pin 26 is providedfor each of the two barrels which are designated upper barrel 27 andlower barrel 28. The pins 26 are fabricated of an electricallyconductive material. Each pin is an elongate member of substantiallycircular cross section, with a radially extending flange portion 29intermediate its two ends. One end 31 of each pin is adapted forcontacting the primer head of a electrically primed cartridge in amanner hereinafter described in detail. The other end 32 of each of thepins is connected to one of the firing circuits by means of an insulatedwire 33. The pins are otherwise insulated from electrical contact bymeans of insulating sleeves 34.

The firing pins 26 and their insulating sleeves 34 are slidably mountedin bore holes 36 formed in the frame 37 of the firearm. Each of the boreholes includes an inner bore 360 and a large outer bore 36b. An annularshoulder 360 is formed between the inner and outer bores.

Means is provided for urging each of the firing pins 26 forward intogood electrical contact with the primer heads of cartridges in theweapon when the breech is closed and locked. This means includes anactuator block 38 and resilient spring members 39. The block 38 isformed to include bore holes 3811 in which the outer ends of the firingpins 26 are slidably mounted. The springs 39 are constrained between theactuator block 38 and the flange portions 29 of the firing pins. Theactuator block is attached to the locking bolt 41 of the firearm andadapted for movement forward and rearward with it.

Thus. when the bolt is moved forward into its locking position. thesprings 39 urge the firing pins 26 forward into contact with the primerheads 42 of cartridges 43 in the firing chamber. The cartridges alsoinclude an outer casing 44 having a metalllic base portion 44a which isgrounded electrically to the weapon frame 37 by direct contact with thewalls of the firing chamber. and a charge of powder 46 in the casing 44.

The primer heads 42 include a metallic shell 42a press-fitted into thebase portion 44a of the cartridge casing. an electrical contact 42bmounted in the shell 42a and electrically insulated therefrom by aninsulator 42c. and a charge of priming compound 42d. The firing pins 26contact only the electrical contacts 42b of the primer heads. and thepriming compound 42d is ignited by the passage of an electric currentbetween the electrical contact and the primer shell. Ignition of thepriming compound causes ignition of the powder charge 46.

Means is provided for retracting the firing pins 26 to preventaccidental discharge of the weapon whenever the breech is unlocked oropen. This means includes resilient spring members 47 which areconstrained between the flange portions 29 of the firing pins and theannular shoulders 36c of the firing pin bores 36. The springs 47 have asmaller spring constant than do the springs 39 so that they will notprevent the firing pins from making good electrical contact with theprimer heads when the bolt is in its locked position. When the bolt isunlocked and the tension in the springs 39 is relaxed. however. thespring members 47 urge the firing pins 26 back to they cannot makecontact with the cartridges.

While the firing pins have been described with reference to tinover-under type of gun. the system of retractable insulated tiring pinsactuated by the breech locking mechanism can be iiipplied equally wellin side-by-side weapons. drillings. tierlings. and single-barrel guns.including both single-shot weapons and repeaters ot' the pump action andautomatic types.

A preferred embodiment of a trigger mechanism for converting mechanicalmovement into electrical signals without electrical contacts is shown inFIG. 3. This mechanism includes a pivotally mounted trigger 48 and aflexible arm 51. one end of which is secured to the weapon frame 37. Thetrigger 48 includes a heel 48a which engages the free end of theflexible arm 51. The arm 51 is fabricated of a resilient material. suchas spring steel. and strain gages R-52 and R-53 tire affixed to itsupper and lower surfaces. respectively. When the trigger 48 is pulled.the heel 48a is moved upward. flexing the arm 51 and straining thestrain gages R-52 and R-S3 in opposite directions.

As can be seen in FIG. 4. strain gages R-52 and R-53 are connected asopposite arms in a conventional bridge circuit. The bridge circuit alsoincludes balancing resistors R-54 and lR-56. Resistor R-56 is a variableresistor which permits balancing of the bridge when the trigger 48 is inits rest position. The output of the bridge circuit is applied to theinput terminals of a conventional differential amplifier A-57 A throughresistors R-58 and R-59. When the trigger is in its rest position. thevoltage at output terminal 61 of the differential amplifier A-57 ishigh. When the trigger is pulled and the bridge is unbalanced. thevoltage at output terminal 61 is low. A resistor R-62 is connectedbetween the output terminal 61 and one of the input terminals of thedifferential amplifier. This resistor provides hysteresis in the actionof the differential amplifier so that the transition from high to lowoutput voltage will be a sharp one.

Means is provided for adjusting the travel and pull of the trigger 48.The means for adjusting the travel includes an adustable stop 63 and afixed stop 64 adapted for engaging the lower and upper surfaces.respectively. of the forward trigger arm 48b. As illustrated. theadjustable stop 63 can be a screw threadably mounted in the gun frame37. The pull is determined primarily by a resilient spring member 66constrained between the forward trigger arm 48b and the gun frame 37. Inthe rest position. this spring urges the forward trigger arm intoengagement with the fixed stop 64. This system permits the travel andpull of the trigger to be adjusted to very small values without dangerof accidental discharge by jarring or dropping the gun. This safety ispossible because the spring arm 5] has a low mass and is not stressedwhen the trigger is in its rest position.

The sensitivity of the trigger, or the threshold for firing is basedupon the difference in resistance between the two strain gages. Thissensitivity is primarily dependent upon the spring constant of theflexible arm. the properties of the strain gages, and the design of thecircuit to which they are connected. Thus. the sensitivity can beadjusted independently of the travel and pull of the trigger.

in alternative trigger mechanism and trigger circuit is shown in FIGS. 5and 6. This mechanism includes a pivotally mounted trigger 67 and asealed pressure sensitive switch SW- 68. This switch is a normally open,single-pull single-throw switch which requires only a few ounces offorce for actuation. When the trigger 67 is pulled. the trigger actuatorarm 67a bears down upon the switch SW-68. closing it. This switch isconnected into a circuit which includes resistors R-69 and R- 71 and acapacitor 072. This circuit provides rapid genera- .1011 of noise-freepulses. When a switch SW-68 is open. the oltage at output terminal 73 ishigh, and when the switch is closed this output voltage steps to the lowvalue.

Means is also provided for adjusting the travel and pull of thisalternative trigger arrangement. This means for adjusting the travelincludes an adjustable stop 74 and a fixed stop 76 As iiiown in FIG. 5.the adjustable stop 74 can conveniently include a screw threadablymounted in the gun frame 37. The pull is provided by a resilient springmember 77 constrained between the actuator arm 67a and the frame 37. Theamount of pull is determined by the spring constant of this spring.Because of the relatively low mass of the trigger and actuator arm. thetravel and pull can be adjusted to very low values without danger ofaccidental discharge of the weapon due to arring.

t preferred control circuit based on NAND positive logic tor atwo-barrel. single-trigger weapon is shown in FIG. 7. This circuit canbe used with either of the trigger arrangements and trigger circuitsheretofore described. In this circuit. logic pulses from the triggercircuits are timed, sequenced. and distributed to the firing circuits toprovide firing of the barrels in a predetermined order. This circuitalso prevents simultaneous discharge of the two barrels, or doubling.Doubling generally occurs because upon the discharge of the cartridge inthe first barrel. a weapon recoils, drawing the trigger away from theshooter's trigger finger. This provokes an uncon- 5CIOUS pull of thetrigger. a purely reflex action on the part of all shooters. If thissecond pull were allowed to actuate the second firing circuit and itscartridge, an apparent double discharge would occur. The seconddischarge not only wastes ammunition. but increases the recoil of theweapon and is thus painful to the shooter.

This logic circuit includes an input terminal 81 adapted for receivinglogic pulse signals from the trigger circuits. From the input terminals.the pulses pass to a first NAND-gate 82. then o a second NAND-gate 83and then to a one-shot multivibrator 84. The 0 output of themultivibrator 84 is connected to the clock input of a J-K flip-flop 86and also to one input terminal of NAND-gates 87 and 92. These NAND gatescontrol The firing of the upper and lower barrels, respectively. Theoutput of NAND-gate 87 is connected to the input of NAND- gate 88. andthe output of NAND-gate 88 is connected to output terminal 89 forconnection to the upper barrel firing circuit. The output of theNAND-gate 92 is connected to the nDut of NAND-gate 93. and the output ofNAND-gate 93 is connected to an output terminal 94 for connection to thelower barrel firing circuit. The 1 output of the flip-flop 86 isconnected to a second input terminal of the NAND-gates 87 and 92. The 0output of the flip-flop 86 is connected to the clock input of a secondJ-K flip-flop 91. The 1 output of the tlip-flop 91 is connected to athird input terminal of NAND- gate 87. and the Ooutput is connected to athird input terminal of the NAND-gate 92.

Operation of this logic circuit can now be briefly described as follows.The upper barrel can fire only when the output at terminal 89 is high,which occurs only when all of the inputs to low. With the trigger in itsrest position, the input at terminal 81 is high, and the output ofNAND-gate 83 is likewise high. When the trigger is pulled, the input atterminal 81 goes low and so does the output of NAND-gate 83. Thistriggers the multivibrator 84, making its 0 output high and firing theupper barrel. The time constant of the multivibrator 84 is chosen sothat its pulse duration is shorter than the shooters reflex time, whichis on the order of to milliseconds. Since a J-K flipflop is actuated bythe trailing edge of a positive pulse, i.e., a high to low transition,at its clock input, flip-flop 86 is actuated at the end of the'positivepulse from multivibrator 84. At this time, the logic states of flip-flop86 are reversed, with its 0 output being high and its 1 output low.

The reflexive trigger pull again causes the output of multivibrator 84to go high. However, this time neither barrel fires since neitherNAND-gate 86 nor NAND-gate 92 has all of its inputs high. At the end ofthis second positive pulse from multivibrator 84, flip-flop 86 is againactuated, returning to its original state. The 0 output of flip-flop 86is connected to the clock input of flip-flop 91, and the transition ofthis output from high to low actuates flip-flop 91, making its 0outputhigh and its 1 output low. At this time, the inputs to NAND-gate92 from the two flip-flop are both high, and the input frommultivibrator 84 is low. The next pull of the trigger drives the outputof multivibrator 84 high, thus firing the lower barrel.

Means is provided for resetting the flip-flops 86 and 9l to theiroriginal logic states. This means includes a switch SW-96 which in thepreferred embodiment is actuated by opening the gun action. Thus, witheach loading or opening of the action, the control circuit is reset toits original state.

Means is also provided for reversing the firing order of the twobarrels. This means includes a switch SW-97 which provides means formanually reversing the initial logic state of flip-flop 91. The RCcircuits 98 and 99 associated with switch 97 are provided to assurenoise-free operation of the sequence selector switch.

An alternative control circuit for a two-barrel gun with a singletrigger is shown in FIG. 8. This circuit is somewhat simpler than thecircuit of FIG. 7 in that is includes only one J-K flip-flop. Theremaining elements of the circuit correspond generally to the elementsof the FIG. 7 circuit and have been designated accordingly. In thiscircuit, the NAND-gates 187 and 192 each derive two of their inputs fromthe outputs of NAND-gates 182 and one-shot multivibrator 184. The thirdinput of NAND-gate 187 is connected to the 1 output of J-K flip-flop186, and thethird input of NAND-gate l92 is connected to 0 output ofthis flip-flop.

Operation of this alternative circuit can be described briefly asfollows. Initially, the input to NAND-gate 187 from flip-flop 186 ishigh, and the inputs from NAND-gate 182 and multivibrator 184 are low.All three inputs to NAND-gate 192 are low. Upon the first pull of thetrigger, the outputs of NAND- gate 182 and multivibrator 184 90 high,thus firing the upper barrel. In this circuit, the time constant ofone-shot multivibrator 184 is adjusted such that the duration of itspositive pulse is longer than the reflex time of the shooter, that is onthe order of 50 to 200 milliseconds. Thus, the flip-flop 186 remains inits initial state until after the reflex pull has occurred. Withflipflop 186 in its initial state, its 0 output is low, thus preventingfiring of the lower barrel. At the ends of the positive pulse frommultivibrator 184, flip-flop 186 is actuated and its logic states arereversed. At this time, the input to NAND-gate 192 from flip-flop 186 ishigh, and the inputs from NAND-gate 182 and multivibrator 184 are low.All inputs to the NAND- gate 187 are low. The next trigger pull causesthe remaining inputs to NAND-gate 192 to go high, thus firing the lowerbarrel.

Means is provided for resetting the flip-flop 186 to its initial logicstate. This means includes a switch SW-196 which is actuated by openingthe gun action. Thus, the logic circuit is reset to its original statewith each loading of the gun or opening of the action.

Means is also provided for reversing the firing sequence of the barrels.This means includes a switch SW-l97 which permits manual reversal of theinitial logic state of flip-flop 186.

The firing delay introduced by either of the control circuits heretoforedescribed is only a small fraction of a millisecond, or essentiallyzero, as compared with a mechanical lock which has a lock time on theorder of 7 to 20 milliseconds. This rapid response is possible becausefiring is done on the leading edge of the logic pulses from the triggercircuit, the only source of delay being the propagation time of thelogic circuits.

As will be apparent to those familiar with the art, the choice of inputpulse polarity and NAND positive logic is one of convenience andutility, and different polarities and logic schemes can be used ifdesired.

A preferred embodiment of a firing circuit is shown in FIG. 9. Thiscircuit is suitable for use with either of the trigger means and controlcircuits heretofore described. In a multibarrel weapon, one such firingcircuit is provided for each of the barrels.

The firing circuit comprises a silicon controlled rectifier SCR-101,having a cathode 102, an anode 103, and a gate 104. The cathode 102 isconnected to the firing pin 26 of the weapon, and the anode 103 isconnected to a source of electrical energy through safety switch 23. Thegate 104 is connected to an input terminal 106 through a diode-D407 anda resistor R-l08. The input terminal 106 is adapted for connection tothe output of either of the control circuits shown in FIGS. 7 and 8.

operations of the firing circuit can be described briefly as follows. Inthe rest condition, the input at terminal 106 is low, thus holding thegate 104 at a low voltage so that the silicon controlled rectifier doesnot conduct. When the input signal at terminal 106 goes high, thesilicon controlled rectifier is trig- 'gered and firing pin 26 isconnected to the source of electrical energy. This causes current toflow through and ignite the priming compound 42d, resulting in ignitionof the powder 46. The silicon controlled rectifier remains conductiveuntil the flow of current is interrupted by the combustion of thepriming compound and powder.

A resistor R-109 and capacitor C-ll0 are connected between the anode andcathode of the silicon controlled rectifier These components preventself tum-on of the SCR upon sudden application of voltage to thecircuit, such as occurs when the breech or safety switch 23 is closed. Aresistor R-l12 is connected between the gate and cathode to providefurther stabilization of the circuit.

All of the circuits of the ignition system can be powered by smallportable batteries which are easily mounted in the gun. Preferably, thefiring circuits should be powered by a battery which is separate fromthe power source used for the control circuits to avoid the possibilityof introducing extraneous pulses into the logic circuits upon the firingof the barrels. The use of a capacitor across the battery for the firingcircuits has been found to enhance the speed of primer ignition.Switches, such as 23 and 24, can be provided for limiting the drain onthe batteries when the gun is not in use.

Although the ignition system has been described with reference totwo-barrel weapons having a single trigger, it is not limited thereto.It can be utilized in single-barrel guns and in guns with multiplebarrels and multiple triggers. In weapons FIGS. 10 and 11 illustrate anembodiment of the invention which is particularly suitable for use insingle barrel weapons such as automatic, pump action, and single shotguns. The trigger mechanism illustrated in FIG. 10 is generally similarto that shown in FIG. except that the pressure sensitive switch 5W-68has been replaced by a pressure sensitive thyristor or siliconcontrolled rectifier SCR-121. The pressure sensitive ISCR is afour-layer solid state device having a structure generally similar tothat ofa conventional thyristor. It includes an anode electrode 122, acathode electrode 123, and a gate electrode 124. The device is normallynon-conductive between its anode and cathode electrodes and is renderedeonductive, or turned on. by the application of pressure in the regionof the gate electrode 124. Once turned on, the pressure sensitive SCRremains conductive until the current flowing through it falls below apredetermined level. In the embodiment illustrated in FIG. 10, theSCR-121 is disposed in such a manner that the trigger actuator arm 67aapplies a pressure to the gate region of the SCR when the trigger 67 ispulled.

ln the combined trigger circuit and firing circuit illustrated in FIG.11, the anode electrode 122 of the pressure sensitive SCR is connectedto a source of electrical energy, such as +225 volts, through the safetyswitch 23. The cathode electrode 123 is connected to the firing pm of aweapon, such as the firing pin 26 shown in FIG. 2. A resistor R-l26 andcapacitor C-l27 are connected in series between the anode and eathodeelectrodes to prevent accidental triggering of the ECR. A resistor R-l28is connected between the gate and cathode electrodes to provide furtherstabilization of the cireuit.

Operation of the embodiment shown in FIGS. and 11 can be describedbriefly. Let it be assumed that this system has been installed in aweapon adapted for firing electrically primed cartridges, such as thecartridge 43 in FIG. 2. The pressure sensitive SCR is normally in itsnon-conductive state. When the weapon is fired by pulling the trigger67. the actuator arm 67a exerts a pressure on the base region of theSCR, turning on the SCR and connecting the firing pin 26 to the sourceof electrical energy. This causes current to flow through the primingcompound 42d of the cartridge 43. igniting the priming compound anddetonatmg the powder 46. The SCR remains conductive until the flow ofcurrent is inter- :i'upted by the combustion of the priming compound andpowder.

The pressure sensitive SCR can readily be incorporated in iinulti-barrelweapons having a separate trigger for each barrel. in such weapons, aseparate pressure sensitive SCR is provided for each of the triggers,and a circuit of the type shown ll'l FIG. 10 is provided for eachbarrel.

The pressure sensitive SCR can also be incorporated in imulti-barrelguns of the type having a single trigger and mechanical means forsequencing the firing of different barrels, prevention of doubling, andelimination of unconscious pr reflexive trigger pulls. Although varyingwidely in complextty and structural details, single triggers formulti-barrel weapons generally have at least one trip member which isactuated by finger pressure upon the trigger. The trip members typicallyengage the sear members or catches that hold the hammers of gunlocks intheir cocked positions. Actuation of the trip member or members causesthe hammers to be released, firing conventional percussion typecartridges. One example of such a trigger mechanism described in U.S.Pat. No. 3,057,101, issued Oct. 9. 1962 to H. L. Miller et al. Triggermechanisms ofthis type can be adapted for firing electrically primedcartridges by replacing the sear members with pressure sensitive SCRs.removing the hammers. and replactng the mechanical firing pins withelectrical firing pins and eircuits of the type described hereinbefore.With this system, the first conscious trigger pull causes the tripmember to bear against the pressure sensitive SCR associated with thefirst barrel. and the next conscious pull causes the trip member toengage the SCR ofthe second barrel.

From the foregoing, it is apparent that a new and improved tystem forelectronic ignition has been provided for firearms.

This system is capable of long and trouble-free performance since itincludes no electrical contacts other than the contact between thefiring pins and the primer heads of the cartridges. it permits wideadjustments of trigger pull and travel and enables a single trigger tocontrol the firing of a plurality of barrels. Both electrical andmechanical safety provisions are included to prevent accidentaldischarge of the firearm. Only the presently preferred embodiments ofthe invention have been described, and as will be apparent to onefamiliar with the art, certain changes and modifications can be madewithout departing from the scope of the invention as defined by thefollowing claims.

What is claimed is:

1. In an electronic ignition system for selectively firing electricallyprimed ammunition in different barrels of a firearm having a singletrigger, means operably connected to the trigger for producing anelectrical trigger signal each time said trigger is pulled by a shooter,electrically conductive firing pins for contacting the primer heads ofelectrically primed ammunition disposed for being fired through thebarrels of the firearm, one such firing pin being provided for eachbarrel, a source of electrical energy, and electronic means connected tosaid firing pins and to said source for energizing a different one ofsaid firing pins in response to alternate trigger signals.

2. An electronic ignition system as in claim 1 wherein said electronicmeans includes an electronic firing circuit connected to each of saidfiring pins and electronic logic control means intermediate the meansfor producing the trigger signals and the firing circuits for actuatinga different one of said firing circuits in response to alternate triggersignals.

3. An electronic ignition system as in claim 2 wherein said logiccontrol means includes a one-shot multivibrator having first and secondstates and a time constant such that said multivibrator remains in itssecond state for a predetermined period of time shorter than theinterval between an intentional pull of the trigger by the shooter andthe reflexive trigger pull which normally follows a discharge of thefirearm, said mul- :ivibrator being connected in such manner that itswitches to its second state in response to each trigger signal thenreturns to its first state after said predetermined period of time, onetransition of said multivibrator back to its first state serving toinhibit actuation of said firing circuits in response to the nextsuccessive trigger signal, and the next such transition serving toenable one of said firing circuits to respond to the next trigger signalfollowing said transition.

4. An electronic ignition system as in claim 2 wherein said logiccontrol means includes a one-shot multivibrator having first and secondstates and a time constant such that said multivibrator remains in itssecond state for a period of time longer than the interval between anintentional pull of the trigger by the shooter and the reflexive triggerpull which normally follows a discharge of the firearm, saidmultivibrator being connected in such manner that each trigger signaloccurring while said multivibrator is in its first state causes saidmultivibrator to switch to its second state and inhibit actuation ofsaid firing circuits as long as said multivibrator remains in saidsecond state.

S. An electronic ignition system as in claim 1 wherein the means forproducing an electrical trigger signal includes at least one pressuresensitive resistive element disposed for detecting movement of saidtrigger.

ti. An electronic ignition system as in claim 1 wherein the means forproducing an electrical trigger signal includes a flexible memberdisposed for being flexed when the trigger is pulled and an electricalresistance strain gage mounted on one surface of said flexible member,said strain gage being connected electrically in one arm of a bridgecircuit.

An electronic ignition system as in claim 1 wherein the means forproducing an electrical trigger signal includes a pressure sensitiveswitch having no exposed contacts.

l3. An electronic ignition system as in claim 7 wherein said pressuresensitive switch is a pressure sensitive silicon controlled rectifier.

9. In an electronic ignition system for firing electrically primedammunition through the barrel of a firearm, an electrically conductivefiring pin disposed for contacting the primer head of electricallyprimed ammunition disposed for being fired through the barrel, a sourceof electrical energy, a trigger adapted being pulled by a shooterstrigger finger, and a pressure sensitive solid state switching devicedisposed for changing its state of conductivity in response to a pull ofthe trigger, said device being connected for controlling the flow ofenergy from said source to said firing pin in such manner that saidfiring pin is energized in response to a pull of the trigger by theshooter.

10. An electronic ignition system as in claim 9 wherein said switchingdevice is a pressure sensitive silicon controlled recti- 11. In a methodfor constructing an electronic ignition system for firing anelectrically primed cartridge in a firearm, the steps of providing anelectrical firing pin for contacting the primer head of the cartridge,connecting a pressure sensitive solid-state switching device to saidfiring pin and to a source of electrical energy, said switching devicebeing adapted for changing its state of conductivity in response topressure applied thereto, and mounting said switching device inproximity to the trigger of the firearm so that actuation of saidtrigger causes a pressure to be applied to said device, thereby changingthe state of conductivity of said device and energizing said firing pin.

1. In an electronic ignition system for selectively firing electricallyprimed ammunition in different barrels of a firearm having a singletRigger, means operably connected to the trigger for producing anelectrical trigger signal each time said trigger is pulled by a shooter,electrically conductive firing pins for contacting the primer heads ofelectrically primed ammunition disposed for being fired through thebarrels of the firearm, one such firing pin being provided for eachbarrel, a source of electrical energy, and electronic means connected tosaid firing pins and to said source for energizing a different one ofsaid firing pins in response to alternate trigger signals.
 2. Anelectronic ignition system as in claim 1 wherein said electronic meansincludes an electronic firing circuit connected to each of said firingpins and electronic logic control means intermediate the means forproducing the trigger signals and the firing circuits for actuating adifferent one of said firing circuits in response to alternate triggersignals.
 3. An electronic ignition system as in claim 2 wherein saidlogic control means includes a one-shot multivibrator having first andsecond states and a time constant such that said multivibrator remainsin its second state for a predetermined period of time shorter than theinterval between an intentional pull of the trigger by the shooter andthe reflexive trigger pull which normally follows a discharge of thefirearm, said multivibrator being connected in such manner that itswitches to its second state in response to each trigger signal thenreturns to its first state after said predetermined period of time, onetransition of said multivibrator back to its first state serving toinhibit actuation of said firing circuits in response to the nextsuccessive trigger signal, and the next such transition serving toenable one of said firing circuits to respond to the next trigger signalfollowing said transition.
 4. An electronic ignition system as in claim2 wherein said logic control means includes a one-shot multivibratorhaving first and second states and a time constant such that saidmultivibrator remains in its second state for a period of time longerthan the interval between an intentional pull of the trigger by theshooter and the reflexive trigger pull which normally follows adischarge of the firearm, said multivibrator being connected in suchmanner that each trigger signal occurring while said multivibrator is inits first state causes said multivibrator to switch to its second stateand inhibit actuation of said firing circuits as long as saidmultivibrator remains in said second state.
 5. An electronic ignitionsystem as in claim 1 wherein the means for producing an electricaltrigger signal includes at least one pressure sensitive resistiveelement disposed for detecting movement of said trigger.
 6. Anelectronic ignition system as in claim 1 wherein the means for producingan electrical trigger signal includes a flexible member disposed forbeing flexed when the trigger is pulled and an electrical resistancestrain gage mounted on one surface of said flexible member, said straingage being connected electrically in one arm of a bridge circuit.
 7. Anelectronic ignition system as in claim 1 wherein the means for producingan electrical trigger signal includes a pressure sensitive switch havingno exposed contacts.
 8. An electronic ignition system as in claim 7wherein said pressure sensitive switch is a pressure sensitive siliconcontrolled rectifier.
 9. In an electronic ignition system for firingelectrically primed ammunition through the barrel of a firearm, anelectrically conductive firing pin disposed for contacting the primerhead of electrically primed ammunition disposed for being fired throughthe barrel, a source of electrical energy, a trigger adapted beingpulled by a shooter''s trigger finger, and a pressure sensitive solidstate switching device disposed for changing its state of conductivityin response to a pull of the trigger, said device being connected forcontrolling the flow of energy from said source to said firing pin insuch mAnner that said firing pin is energized in response to a pull ofthe trigger by the shooter.
 10. An electronic ignition system as inclaim 9 wherein said switching device is a pressure sensitive siliconcontrolled rectifier.
 11. In a method for constructing an electronicignition system for firing an electrically primed cartridge in afirearm, the steps of providing an electrical firing pin for contactingthe primer head of the cartridge, connecting a pressure sensitivesolid-state switching device to said firing pin and to a source ofelectrical energy, said switching device being adapted for changing itsstate of conductivity in response to pressure applied thereto, andmounting said switching device in proximity to the trigger of thefirearm so that actuation of said trigger causes a pressure to beapplied to said device, thereby changing the state of conductivity ofsaid device and energizing said firing pin.